Fixing device

Abstract

To prevent a reduction in productivity when performing fixing in a job in which different types of recording materials are mixed.SOLUTION: A fixing device comprises: a heating rotating body and a pressure rotating body that apply heat and pressure to a recording material to fix a toner image to the recording material; an acquisition unit that acquires in advance information on a predetermined number of recording materials; and a temperature control unit that controls the temperature of the heating rotating body based on information on basis weights acquired by the acquisition unit. The fixing device defines a job in which different basis weights are mixed as a mixed job, executes the mixed job, and when changing the temperature of the heating rotating body during the mixed job, reduces the amount of change in the temperature of the heating rotating body based on the information on the basis weights of the recording materials acquired by the acquisition unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention relates to a fixing device for fixing a toner image onto a recording material. [Background technology]

[0002] The image forming apparatus has a fixing device that fixes the unfixed toner image on the recording material to the recording material.

[0003] A known fixing device comprises a heating rotating body having a heating source for heating the unfixed toner image, and a pressure roller for pressurizing the heating rotating body (Patent Document 1). The fixing device also has a contact-separation mechanism, which allows the pressure rotating body to move between a position in contact with the heating rotating body and a position separated from it. When the pressure rotating body is in contact with the heating rotating body, a nip is formed by the heating rotating body and the pressure rotating body. When recording material carrying the unfixed toner image is conveyed to this nip, the heat and pressure necessary for fixing are applied at the nip, and the toner on the recording material is fixed.

[0004] When forming a toner image on a recording material, the amount of heat required to fix the toner image varies depending on the type of recording material. Patent Document 1 discloses a technique for changing the temperature of a heating rotating body according to the type of recording material. This appropriately controls the amount of heat supplied to the toner image on the recording material.

[0005] By adjusting the optimal heat level depending on the type of recording material, the image quality of the toner image formed on the recording material improves. On the other hand, changing the temperature for each recording material reduces productivity. Therefore, a fuser unit having both an image quality priority mode and a productivity priority mode allows the user to select the mode to use for fixing according to their purpose. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-242598

Summary of the Invention

Problems to be Solved by the Invention

[0007] In a fixing device having a plurality of modes, in Patent Document 1, the temperature of the heating rotating body is changed according to the type of recording material to be fixed.

[0008] However, when fixing a job in which recording materials having different basis weights are mixed, every time the type of recording material is different, the temperature of the heating rotating body has to be changed, so there is a risk of a decrease in productivity.

[0009] Therefore, the fixing device according to the present invention aims to suppress a decrease in productivity when fixing a job in which recording materials of different types are mixed.

Means for Solving the Problems

[0010] In view of the above problems, the fixing apparatus according to the present invention comprises a heating rotating body that heats the recording material, a pressurizing rotating body that pressurizes the heating rotating body, the heating rotating body and the pressurizing rotating body apply heat and pressure to the recording material to fix the toner image to the recording material, a temperature control unit that controls the temperature of the heating rotating body, an acquisition unit that acquires information on the basis weight of the recording material to be fixed, a mixed job in which recording material of a first basis weight and recording material of a second basis weight smaller than the first basis weight are mixed, in the mixed job one mode can be executed from a plurality of modes including a first mode and a second mode, the first mode prints more sheets per unit time than the second mode, and in the mixed job the acquisition unit can execute multiple modes in the same job When fixing a number of recording materials, information regarding the basis weight of a predetermined number of recording materials is acquired, the temperature control unit sets the temperature based on the information acquired by the acquisition unit, when the first mode is executed, the first temperature is used to fix the recording material of the first basis weight, and the second temperature, which is lower than the first temperature, is used to fix the recording material of the second basis weight, when the second mode is executed, the first temperature is used to fix the recording material of the first basis weight, and the third temperature, which is different from the first and second temperatures, is used to fix the recording material of the second basis weight, and the difference between the first temperature and the second temperature is smaller than the difference between the first temperature and the third temperature. [Effects of the Invention]

[0011] The fixing apparatus according to the present invention makes it possible to improve productivity when fixing jobs in which different types of recording materials are mixed. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic cross-sectional view of the image forming apparatus in this embodiment. [Figure 2] This is a schematic cross-sectional view of the fixing device in this embodiment. [Figure 3] This figure shows the heat distribution of the halogen heater in this embodiment. [Figure 4]This figure shows a block diagram in this embodiment. [Figure 5] This figure shows a temperature table based on the mode in this embodiment. [Figure 6] This is a flowchart for automatically setting the mode in this embodiment. [Figure 7] This figure shows the effects of this embodiment in detailed verification 1. [Figure 8] This figure shows the effects of this embodiment in detailed verification 2. [Figure 9] This is a flowchart for conducting detailed verification 3. [Figure 10] This figure shows the temperature of the heated rotating body in detailed verification 3. [Figure 11] This figure shows the effects of this embodiment in detailed verification 3. [Modes for carrying out the invention]

[0013] The embodiment of the image forming apparatus in this embodiment will be described below with reference to the drawings. While the following description applies to a full-color electrophotographic image forming apparatus having multiple photosensitive drums, this embodiment is not limited to this and can also be applied to monochrome image forming apparatuses and the like.

[0014] <Image forming apparatus> The schematic configuration of the image forming apparatus 1 of this embodiment will be explained with reference to Figure 1.

[0015] Figure 1 shows a full-color image forming apparatus according to this embodiment. The image forming apparatus 1 comprises an image reading unit 2 and an image forming apparatus body 3. The image reading unit 2 reads a document placed on the document glass 21. Light emitted from the light source 22 is reflected by the document and formed on a CCD sensor 24 via an optical system component 23 such as a lens. By scanning in the direction of the white arrows in Figure 1, this optical system unit converts the document into a series of electrical signal data for each line. The image signal obtained by the CCD sensor 24 is sent to the image forming apparatus body 3, where the control unit 100 performs image processing according to each image forming unit, which will be described later. The control unit 100 also accepts external input as an image signal from an external host device such as a print server.

[0016] The main body of the image forming apparatus 3 has four types of image forming units—yellow Pa, magenta Pb, cyan Pc, and black Pd—arranged along the direction of movement of the intermediate transfer belt 204. First, the process of forming a toner image on the intermediate transfer belt 204 will be explained using the yellow image forming unit Pa as an example.

[0017] In Figure 1, the surface of the rotating photosensitive drum 200a is uniformly charged by the charger 201a (charging). Subsequently, the exposure device 31 irradiates the surface of the photosensitive drum 200a with a laser according to the input image data, forming an electrostatic latent image on the surface of the photosensitive drum 200a (exposure). Then, the developing device 202a forms a yellow toner image on the photosensitive drum 200a. The primary transfer roller 203a applies a voltage to the intermediate transfer belt 204 with a polarity opposite to the potential polarity of the yellow toner image. As a result, the yellow toner on the photosensitive drum 200a is transferred to the intermediate transfer belt 204 (primary transfer). Any yellow toner that remains on the surface of the photosensitive drum 200a without being transferred is scraped off by the toner cleaner 207a and removed from the surface of the photosensitive drum 200a. This series of processes is carried out similarly for magenta Pb, cyan Pc, and black Pd. As a result, a full-color toner image is formed on the intermediate transfer belt.

[0018] The toner image on the intermediate transfer belt 204 is transported to the secondary transfer section N2, which is formed by the secondary transfer roller pair 205, 206. In accordance with the timing of the toner image transport, one sheet of recording material S is taken out from the recording material cassettes 8, 9 and fed to the secondary transfer section N2. Then, the toner image on the intermediate transfer belt 204 is transferred to the recording material S (secondary transfer).

[0019] The recording material S onto which the toner image has been transferred is transported to the fuser unit F, where it is fixed by heat and pressure (fixing). The recording material S with the fixed toner image is then discharged into the output tray 7.

[0020] The image forming apparatus 1 can also perform monochrome image formation. When forming a monochrome image, only the black image forming unit Pd among the multiple image forming units is driven.

[0021] When image formation is performed on both sides of the recording material S, once the transfer and fixing of the toner on the first image-forming surface (1st surface) is complete, the recording material S is reversed by passing through a reversal section located inside the image forming apparatus after fixing. Next, the toner on the second image-forming surface (2nd surface) is transferred and fixed, and the material is ejected from the machine and stacked on the output tray 7.

[0022] The process from charging to the discharge of the recording material S, on which the toner image has been fixed, into the output tray 7 is referred to as the image forming process (print job). The period during which image forming is taking place is referred to as the image forming process (print job in progress).

[0023] <Fusing device> Figure 2 shows a schematic diagram of the overall configuration of the belt heating type fixing device F according to this embodiment. In Figure 2, the recording material P is conveyed from right to left. The fixing device F has a fixing belt (hereinafter referred to as the belt) 310 as an endless, rotatable heating rotating body and a pressure pad (hereinafter referred to as the pad) 320 as members that form the nip portion N. The fixing device F also has a heating unit 300 including a heating roller 351 and a steer roller 340, and a pressure roller 330 as a pressure rotating body that faces the belt and forms the nip portion N together with the belt.

[0024] The belt 310 has thermal conductivity and heat resistance, and is a thin-walled cylindrical shape with an inner diameter of 120 mm. In this embodiment, it has a three-layer structure with a base layer, an elastic layer on the outer circumference of the base layer, and a release layer on the outer circumference of the elastic layer. The base layer is 60 μm thick and made of polyimide resin (PI), the elastic layer is 300 μm thick and made of silicone rubber, and the release layer is 30 μm thick and made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The belt 310 is stretched by a pad 320, a heating roller 351, and a steer roller 340.

[0025] The pad 320 is pressed against the pressure roller 330 with the belt 310 in between. The pad 320 is made of LCP (liquid crystal polymer) resin. A lubricating sheet 370 is interposed between the pad 320 and the belt 310. The lubricating sheet 370 is made of a PI (polyimide) sheet coated with PTFE (polytetrafluoroethylene) and has a thickness of 100 μm. The PI sheet has protrusions of 100 μm at 1 mm intervals, which reduces sliding resistance by reducing the contact area with the belt 310. A lubricant is applied to the inner surface of the belt 310 so that the belt 310 slides smoothly against the pad 320. Silicone oil with a viscosity of 100 cSt is used as the lubricant.

[0026] Although the pad 320 is used as a means of forming the nip in the above description, a rotating body such as a roller may also be used.

[0027] The heating roller 351 is a hollow roller with a stainless steel core, and a halogen heater 390 is disposed inside the core, capable of generating heat up to a predetermined temperature. The belt 310 is heated by the heating roller 351, which is heated by the halogen heater 390. The temperature control unit 102 controls the temperature of the belt 310 to a predetermined target temperature according to the type of paper, based on temperature detection by the thermistor 352. The thermistor 352 is positioned in contact with the heating roller 351.

[0028] Furthermore, the heating roller 351 has a gear fixed to one end of its shaft, and is connected to the drive source M1 of the drive roller via the gear to be rotationally driven. The belt 310 is given conveying force by the rotation of the heating roller 351. The rotation of the heating roller 351 may be driven by the pressure roller drive source M0 that rotates the pressure roller 330, or it may be driven by a drive roller drive source M1 separate from the pressure roller drive source M0. In other words, the drive source that rotates the heating roller 351 is not limited to any particular means.

[0029] The pressure roller 330 is a roller with an elastic layer on its outer circumference and a release layer on the outer circumference of the elastic layer. Stainless steel is used for the core metal. The elastic layer is 5 mm thick and made of conductive silicone rubber. The release layer is 50 μm thick and made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The pressure roller 330 is pivotally supported by the fixing frame 380 of the fixing device F. A gear is fixed to one end of the pressure roller 330 and is connected to the pressure roller drive source M0 via the gear to drive rotation. The rotational drive means for the pressure roller 330 is the same as for the heating roller 351, and the rotational drive means is not limited.

[0030] The belt 310 and pressure roller 330 described above form a nip section N. The recording material S carrying the toner image is then gripped in the nip section N, and the heat and pressure necessary for fixing the toner image are applied to it while it is being transported. In this way, the fixing device F fixes the toner image to the recording material P while gripping and transporting the recording material P.

[0031] The fixing frame 380 is provided with a heating unit positioning section 381, a pressure frame 383, and a pressure spring 384. The stay 360 of the heating unit 300 is inserted into the heating unit positioning section 381, and the stay 360 is fixed to the heating unit positioning section 381 by fixing means (not shown).

[0032] After the stay 360 is fixed, the pressure frame 383 moves due to a drive source (not shown) and a cam, thereby applying pressure to the pad 320 via the belt 310 on the pressure roller 330.

[0033] Here, in the heating unit positioning section 381, the side opposite the pressure roller 330 is designated as the pressure direction restricting surface 381a, and the abutting surface in the insertion direction of the heating unit 300 is designated as the transport direction restricting surface 381b.

[0034] The print speed is 630 mm / s, the pressure applied within the fuser nip is 1000 N, and the target temperature of the belt 310 when fixing the toner image to the recording material S is as shown in Figure 5.

[0035] A steer roller 340 is positioned upstream of the nip section N as a means for maintaining the conveying posture of the belt 310. The steer roller 340 is biased by a spring supported by the frame of the heating unit 300 and is a tension roller that applies a predetermined tension to the belt 310, rotating in a driven manner relative to the belt 310. The tension from the spring is 50N, which applies tension to the belt 310 from within.

[0036] The steer roller 340 has a pivot point at one end of its longitudinal axis or near the center, and rotates relative to the belt 310 to generate a tension difference in the front and rear directions, thereby controlling the position of the belt 310 in the main scanning direction. In this embodiment, the pivot point is located in the longitudinal center, but a configuration with the pivot point at one end of the longitudinal axis may also be used. The steer roller 340 is biased by a spring supported by the frame of the heating unit 300, and also acts as a tension roller that applies a predetermined tension to the belt 310. The tension from the spring is 50N, and the belt position in the main scanning direction is controlled by applying tension to the belt 310.

[0037] The steer roller 340 is intended to stabilize the behavior of the belt introduced into the nip section N. The steer roller 340 is a 1mm thick hollow pipe made of stainless steel and rotates in a driven manner relative to the belt.

[0038] For the surface roughness, an arithmetic mean roughness Ra = 0.05 [μm] was used, which represents a relatively smooth state. However, if the belt driving torque and wear on the inner surface are not issues, a higher surface roughness of the steer roller 340 is acceptable, and the surface may be formed with, for example, a rubber material.

[0039] Figure 3 shows the configuration of the halogen heater 390 and thermistor 352 in this embodiment. Six halogen heaters 390 are used in this embodiment. Figure 3 shows the heat generation distribution of each of the six halogen heaters 390. In the width direction of the belt 310, heater (1) shown in Figure 3 generates more heat in the central part than at the ends. Heater (2) also generates more heat at the ends than in the central part in the width direction of the belt 310. This is to equalize the heat generation distribution between the center and the ends in the width direction of the belt 310. The thermistor 352 is positioned at 3 mm, 100 mm, and 150 mm from the center of the heating roller 351 in the width direction of the belt 310, and constantly measures the temperature of the heating roller 351. Using this temperature, the temperature of the belt 310 is predicted from the relative relationship between the heating roller 351 and the belt 310, and the fixing temperature is controlled.

[0040] In this embodiment, the configuration is as shown in Figure 3, but it is not limited to this. The number of halogen heaters 390, the number of thermistors 352, the positional relationship between the halogen heaters 390 and thermistors 352, and the heat generation distribution of the halogen heaters 390 may be changed. In addition, to directly observe the temperature of the belt 310, the thermistor may be brought into contact with the belt 310 and the temperature may be measured.

[0041] The block circuit of this embodiment is shown in Figure 4. This shows the control system of the image forming apparatus including the fixing device F of this embodiment. The control unit 100 controls the entire image forming apparatus, to which the operation unit 101, consisting of a liquid crystal touch panel and buttons, is connected. The image forming apparatus starts operating based on the input of various conditions from the user via the operation unit 101.

[0042] Information such as the size and basis weight of the recording material (paper) to be fed is transmitted to the acquisition unit 110 from the operation unit 101, etc. When printing starts, the acquisition unit 110 acquires the print information in advance, and the paper type information for the first 15 sheets is stored in the acquisition unit 110. (In this embodiment, 15 sheets of paper type information are acquired, but this number is not limited.) Furthermore, the temperature of the central part of the heating roller 351 in the longitudinal direction, the temperature between the center and the end, and the temperature information of the end are transmitted to the control unit 100 from the information acquisition means, thermistors 352a, 352b, and 352c.

[0043] The image forming apparatus 1 of this embodiment has a productivity-priority mode (first mode) that prioritizes productivity and an image quality-priority mode (second mode) that prioritizes image quality, and toner image fixing can be performed by these modes. Furthermore, the productivity-priority mode has multiple types of modes, and toner image fixing can be performed by the multiple types of modes. For example, the image forming apparatus 1 of this embodiment has a thick paper mode (fourth mode) that prioritizes the productivity of thick paper, a thin paper mode (fifth mode) that prioritizes the productivity of thin paper, and a balanced mode that prioritizes the productivity of paper with a basis weight between thin paper and thick paper. In this way, productivity can be increased by providing multiple types of modes according to the basis weight of the recording material to be printed. Therefore, thin paper is defined as 64 g / m². 2 and 91g / m 2 In jobs where different recording materials are mixed, fixing is performed at the same temperature when using thin paper mode. However, in thick paper mode, the temperature of belt 310 must be changed from 160°C to 170°C. Therefore, 64g / m 2 and 91g / m 2 In jobs involving a mixture of recording materials, fixing in thin paper mode is more productive than fixing in thick paper mode. In other words, for jobs involving a mixture of recording materials with a basis weight below a certain threshold, fixing in thin paper mode is more productive than fixing in thick paper mode. Similarly, thick paper is defined as 221 g / m². 2 and 257g / m 2In a mixed job with recording materials, when fixing is performed in the thick paper mode, fixing is performed at the same temperature. However, in the thin paper mode, the temperature of the belt 310 must be changed from 170 °C to 175 °C. Since the temperature of the belt 310 must be changed in this way, image formation may have to be interrupted. Therefore, 221 g / m 2 and 257 g / m 2 In a mixed job with recording materials, productivity tends to be higher when fixing is performed in the thick paper mode than in the thin paper mode. That is, when recording materials with a predetermined basis weight or more are mixed, productivity tends to be higher when fixing is performed in the thick paper mode than in the thin paper mode.

[0044] Incidentally, the productivity mentioned here refers to the number of sheets printed per unit time. It is expressed that if the number of sheets printed per unit time is large, the productivity is high, and if the number of sheets printed per unit time is small, the productivity is low. Productivity is changed by the conveyance speed of conveying the recording material, changing the interval between the recording materials, the presence or absence of downtime, etc.

[0045] Specifically, as an example, 52 to 105 g / m 2 is defined as thin paper, 106 to 220 g / m 2 is defined as plain paper, and 221 to 350 g / m 2 is defined as thick paper. In this embodiment, in the thin paper mode, the range of thin paper is set to the same temperature. Similarly, in the thick paper mode, the range of thick paper is set to the same temperature, and in the balance mode, the range of plain paper is set to the same temperature. The range in which fixing can be performed at the same temperature is changed according to the mode. Thereby, productivity can be improved according to the basis weight.

[0046] On the other hand, the fuser unit F also has a quality priority mode. The quality priority mode is a mode that prioritizes the quality of the formed image. Therefore, it changes the temperature more precisely according to the basis weight than the mode that the productivity priority mode has. The quality of the toner image formed on the recording material depends on the amount of heat applied to the toner image. There is an optimal temperature depending on the basis weight of the recording material, and by applying this optimal temperature, the quality can be improved. The quality priority mode sets the temperature precisely according to the basis weight and type (coated paper or uncoated paper) of the recording material. Therefore, when printing a mixed job with different basis weights in quality priority mode, the belt 310 temperature is changed more often than in productivity priority mode. When changing the belt 310 temperature, time must be allocated for the temperature change, which tends to lower productivity. Therefore, when printing a mixed job in quality priority mode compared to productivity priority mode, the quality tends to be higher when printing in quality priority mode than in productivity priority mode. Also, when printing in quality priority mode, productivity tends to be lower than when printing in productivity priority mode.

[0047] If recording materials of various basis weights are fixed at the same temperature, there is no need to have multiple productivity priority modes. However, when recording materials of various basis weights are fixed at the same temperature, there is a risk of insufficient or excessive heat being applied. Therefore, this embodiment has multiple productivity priority modes. In this embodiment, a configuration with three productivity priority modes is used, but this is not limited to this. Modes can be selected by automatic determination using 15 sheets of paper type information from the contents of the acquisition unit 110 inside the image forming apparatus (third mode), or by the user manually setting the mode from the user mode. Figure 5 shows the temperature tables for the thin paper mode, balance mode, thick paper mode, and image quality priority mode.

[0048] Figure 5 shows the temperature tables for the cardboard mode, thin paper mode, balance mode, and image quality priority mode. The temperature is set according to the basis weight of the recording material. In the fixing device F, which has multiple modes, the temperature of the heating rotating body is changed according to the basis weight of the recording material being fixed.

[0049] However, in mixed jobs where recording materials with different basis weights are mixed, the temperature of belt 310 must be changed each time the basis weight of the recording material changes. It is possible to solve the problem of changing the temperature by extending the range over which fixing is performed at the same temperature, as shown in the productivity priority mode in Figure 5. However, if the basis weight of the recording material differs significantly within the same job, the temperature of belt 310 must be changed. The more the temperature of belt 310 is changed, the longer the temperature change time becomes. If the temperature change time is long, image formation must be interrupted, resulting in downtime.

[0050] Therefore, the fixing device F according to this embodiment aims to suppress the decrease in productivity when fixing jobs in which recording materials with different basis weights are mixed.

[0051] <Detailed Verification 1> The productivity priority mode of this embodiment has a third mode, which is a mode that automatically determines which of the multiple modes available to the productivity priority mode to apply. The details are described below.

[0052] The image forming apparatus 1 or fixing apparatus F of this embodiment has an acquisition unit 110 that acquires information about the recording material in advance before starting image formation. The acquisition unit 110 acquires information about the basis weight of a predetermined number of recording materials (15 in this embodiment). It is not limited to basis weight; for example, information about the type of paper may also be acquired.

[0053] The case in which fixing is selected using the third mode will be explained. The productivity priority mode in this embodiment has a cardboard mode, a thin paper mode, and a balanced mode. Therefore, based on the information acquired by the acquisition unit 110, the temperature control unit 102 selects whether to perform fixing in cardboard mode, thin paper mode, cardboard mode, or balanced mode. In this case, the mode with the smallest temperature change is selected.

[0054] Let's explain with an example. The acquisition unit 110 selects the first 5 out of 15 sheets of recording material for which it can acquire information, and the first 5 sheets are made of high-quality paper weighing 100 g / m². 2 (Mondi100 paper) and the following 10 sheets of coated paper 300g / m² 2 The print was done on UPM Finenesse Gloss 300 paper.

[0055] The above example shows the results when printed using the third mode and the thin paper mode. Note that the paper weight is 52-105 g / m². 2 Thin paper, 106-220 g / m² 2 Standard paper, 221-350 g / m² 2 We define thick paper as cardboard, and in this example, thin paper is being printed on, so the user must manually select the mode, and therefore the thin paper mode is selected. For this reason, we will present the case where fixing is performed in thin paper mode as a comparative example. Referring to the temperature table in Figure 5c, the temperature is 100 g / m². 2 Printing begins at a temperature of 165°C on high-quality paper, 300g / m². 2 The temperature of the coated paper must be switched to 180°C midway through the process. In this fixing configuration, if the temperature difference is greater than 5°C, printing must be interrupted and the fuser temperature must be adjusted to the new temperature. Therefore, a waiting time is required to adjust the temperature.

[0056] In the third mode of this embodiment, the mode is selected according to the steps in the flowchart of Figure 6. At the start, the power of the main unit is turned ON (S101), and a job is submitted by the user (S102). The acquisition unit 110 acquires information regarding the basis weight of the recording material. In addition to the basis weight, the paper type (basis weight, surface quality, shape) of the printed content is also acquired. In this embodiment, the basis weight information is used (S103). Here, the first five sheets are 100g / m² of high-quality paper. 2 (Mondi100 paper) and the following 10 sheets of coated paper 300g / m² 2 Since printing was performed using UPM Finenesse Gloss 300 paper, this example will be used for explanation. Afterward, the temperature change amount for each paper type is calculated for each mode (S104). The results of the calculation are shown in the table below.

[0057] [Table 1]

[0058] In thin paper mode, the temperature change is 15°C. In balanced mode, the temperature change is 10°C. In thick paper mode, the temperature change is 5°C. Therefore, the mode is automatically selected as thick paper mode, which has the smallest temperature change (S105), and the printing mode is determined (S106).

[0059] Figure 7 shows the results of a comparison with the comparative example. In the comparative example (dashed line), paper was fed in thin paper mode, while in the third mode, paper was fed in thick paper mode. In the comparative example, a 10-second time was required to switch temperatures, but in the third mode (solid line), by feeding paper in thick paper mode, it is possible to complete printing without downtime. As a result, it is possible to suppress the decrease in the number of printed sheets per unit time in jobs where recording materials with different basis weights are mixed.

[0060] Using a similar verification method, we will compare the results when fixing is performed in the third mode versus when fixing is performed in the image quality priority mode. The first basis weight is 300g / m². 2 And a basis weight of 100g / m², which is smaller than the first basis weight. 2This is the second basis weight. The relative sizes of the first and second basis weights are not limited to this; they can be different. When fixing is performed in the third mode, the cardboard mode is used. Therefore, when a recording material with the first basis weight is fixed, the temperature of the belt 310 is controlled with a target of 175°C (first temperature). The first temperature is the target temperature for uncoated paper. In this case, the recording material with the first basis weight is coated paper. Even with coated paper, the temperature of the belt 310 is controlled with a target of 175°C (fifth temperature). When a recording material with the second basis weight is fixed, the temperature of the belt 310 is controlled with a target of 170°C (second temperature). When fixing is performed in image quality priority mode, for the first basis weight, the temperature is 182°C (sixth temperature) for coated paper and 175°C (third temperature) for uncoated paper. When a recording material with the second basis weight is fixed, the temperature of the belt 310 is controlled with a target of 165°C (fourth temperature). The temperature difference between the first and second temperatures is 5°C, and the temperature difference between the third and fourth temperatures is 10°C. Therefore, in a mixed job where recording materials of the first and second basis weights are mixed, fixing in the third mode results in a smaller temperature difference than fixing in the image quality priority mode. This reduces the time required to adjust the temperature of the belt 310, thereby improving productivity.

[0061] Furthermore, when fixing is performed in image quality priority mode, fixing is performed at 182°C for the first basis weight and coated paper. If 182°C is the sixth temperature, the difference between the second and fifth temperatures is 5°C, and the difference between the sixth and fourth temperatures is 17°C. Even in jobs where coated and uncoated paper are mixed, the time required to adjust the temperature of the belt 310 is reduced, making it possible to improve productivity.

[0062] In this embodiment, we have shown an example where the first temperature and the fifth temperature are the same, but this is not the only example; they may be different temperatures.

[0063] <Detailed Verification 2> We conducted the study assuming a different use case than that of Detailed Verification 1. Specifically, while Detailed Verification 1 involved a job with a mixture of two types of recording materials, Detailed Verification 2 involved a job with a mixture of three types of recording materials.

[0064] For example, the first four sheets are made of coated paper at 128 g / m². 2 (OK Topcoat 128 paper) is used. 68g / m² of high-quality paper is used for the 5th to 8th sheets. 2 (CS-068 paper) is used. High-quality paper (209g / m²) is used for sheets 9-12. 2 (GF-C209 paper) is used. 350g / m² coated paper is used for sheets 13-15. 2 Printing was performed using UPM Finenesse Gloss 350 paper. When the third mode of this embodiment is selected, the temperature table refers to Figure 5, and the mode is selected according to the steps of the flowchart in Figure 6.

[0065] At the start, the main unit is powered ON (S101), and a job is submitted by the user (S102). The acquisition unit 110 acquires information about the recording material (S103). This will be explained using an example of the recording material used in Detailed Verification 2. Subsequently, the temperature change amount for each paper type is calculated for each mode (S104). The calculation results are shown in Table 2 below. Figure 8 shows the changes in each mode and fixing temperature settings.

[0066] [Table 2]

[0067] In thin paper mode, the temperature difference is 25°C. Specifically, coated paper is 106-128 g / m². 2 From high-quality paper 64-79 g / m² 2 The temperature changes by 5°C when switching. High-quality paper 64-79 g / m² 2 From high-quality paper 181-220 g / m² 2 The temperature changes by 5°C when switching to this setting. High-quality paper 181-220 g / m² 2 From coated paper 326-350 g / m² 2 The temperature changes by 15°C when switching to the other setting. Therefore, the total temperature change is 25°C.

[0068] In balance mode, the temperature change is 35°C. The breakdown is as follows: coated paper 106-128 g / m². 2 From high-quality paper 64-79 g / m² 2 Change the temperature by 10°C when switching. High-quality paper 64-79 g / m² 2 From high-quality paper 181-220 g / m² 2 When switching, change the temperature by 10°C. High-quality paper 181-220 g / m² 2 From coated paper 326-350 g / m² 2 The temperature changes by 15°C when switching to the other setting. Therefore, the total temperature change is 35°C.

[0069] In cardboard mode, the temperature difference is 35°C. Specifically, coated paper is 106-128 g / m². 2 From high-quality paper 64-79 g / m² 2 When switching, change the temperature by 10°C. High-quality paper 64-79 g / m² 2 From high-quality paper 181-220 g / m² 2 When switching, change the temperature by 15°C. High-quality paper 181-220 g / m² 2 From coated paper 326-350 g / m² 2 The temperature changes by 10°C when switching. Therefore, the total temperature change is 35°C.

[0070] Based on these results, the thin paper mode, which has the smallest difference, is automatically selected (S105), and the printing mode is determined (S106).

[0071] In this instance, when selecting the thin paper priority mode, the temperature change was 25°C, but for coated paper of 128 g / m², the temperature change was 25°C. 2 From high-quality paper 68g / m² 2 When switching temperatures, the difference is only 5°C, from 170°C to 165°C. Also, high-quality paper 68g / m² 2 From 209g / m 2 When switching temperatures, the difference is only 5°C, from 165°C to 170°C. The temperature transitions are from 170°C to 165°C, and then from 165°C to 170°C. Therefore, it is possible to automatically adjust the temperature to a uniform 170°C during printing and feed the paper through.

[0072] <Detailed Verification 3> Detailed Verification 1 and 2 were examined based on different use cases. Detailed Verification 3 considers the case where the number of recording materials printed exceeds the number of recording materials that the acquisition unit 110 can acquire at one time.

[0073] When the third mode is selected, verification was performed when printing with different basis weights. This time, the verification involved increasing the number of sheets fed through the paper. Since the acquisition unit 110 can acquire information on up to 15 sheets of recording material, the 20th sheet was printed this time (verification of modes exceeding 15 sheets).

[0074] For example, sheets 1-15 use thin, high-quality paper of 105 g / m². 2 (GF-C104 paper), and 300g / m² coated paper for sheets 16-20. 2 Printing was performed using UPM Finenesse Gloss 300 paper. In the third mode of this embodiment, the temperature table is also referred to in Figure 5, and the temperature table (mode) is selected according to the steps of the flowchart in Figure 9.

[0075] At the start, the main unit is powered ON (S201), and a job is submitted by the user (S202). The acquisition unit 110 acquires information about the recording material (S203). Here, sheets 1 to 15 are 105g / m² high-quality paper. 2 (GF-C104 paper), and 300g / m² coated paper for sheets 16-20. 2 I will explain using UPM Finenesse Gloss 300 paper as an example. After that, the temperature change amount for each paper type is calculated for each mode (S104). As a result of the calculation, sheets 1 through 15 were all printed on thin, high-quality paper at 105 g / m². 2(GF-C104 paper) In thin paper mode, the temperature change amount is 0 (S205). Therefore, thin paper mode is selected when printing starts and printing begins (S207). In this case, the number of sheets to be printed is greater than 15 (S208), so when the number of sheets to be printed exceeds 1 (S209), the acquisition unit 110 acquires information about the recording material (S210). Therefore, the paper information for 15 sheets is always acquired in advance, such as sheets 2-16, sheets 3-17, etc., and the temperature change amount is calculated again (S211). As a result, the table with the smallest change amount calculated for each table is selected. In this case, thick paper mode is selected (S212). Based on this selection result, the printing mode is reset (S213). This is repeated until printing is finished (S214).

[0076] As a result, in the comparative example, when printing in thin paper mode, as shown in Figure 10a, the table is on the thin paper side for the first 15 sheets, and the temperature switches from the 16th sheet onwards. Therefore, a 10-second downtime occurs when the temperature switches. When the third mode is selected and printing is performed, as shown in Figure 10b, the first sheet is in thin paper mode, but from the second sheet onwards, the temperature can be changed based on the information acquired by the acquisition unit 110. This changes the temperature to that of thick paper mode. This makes it possible to suppress the occurrence of downtime due to temperature changes.

[0077] As a result, as shown in Figure 11, in the third mode, the temperature difference is 5°C, so there is no waiting time for switching, and it is possible to complete printing up to the 20th page without any downtime.

[0078] As shown in Figure 5, the image forming apparatus 1 of this embodiment has a predetermined temperature table depending on the basis weight and paper type (for example, coated paper or uncoated paper) of the recording material. The third mode of this embodiment selects a table with a small amount of temperature change from the predetermined temperature table and uses it for fixing. However, it is not limited to this. Alternatively, the control unit 100 may perform calculations from the recording material information acquired by the acquisition unit 110 to reduce the amount of temperature change, calculate the optimal temperature as a result of the calculation, and control the temperature of the belt 310. In other words, instead of selecting a temperature table, the temperature control unit 102 calculates the temperature from the information of the acquisition unit 110. This makes it possible to reduce the amount of temperature change and improve productivity during mixed jobs.

[0079] Furthermore, the user can select the mode to be used for fixing. First, they choose between productivity priority mode and image quality priority mode. If image quality priority mode is selected, the toner image is fixed at the temperature specified for image quality priority mode. On the other hand, if productivity priority mode is selected, one of the multiple modes available in productivity priority mode—in this embodiment, the third mode, thick paper mode, thin paper mode, and balanced mode—is selected, and fixing is performed. This allows the user to select the optimal mode depending on the recording material being printed.

[0080] As described above, in this embodiment, the recording material can be fixed by the third mode. In the third mode, the temperature of the belt 310 is controlled based on information about the recording material (basis weight and paper type) acquired by the acquisition unit 110 before the recording material is fixed. When controlling the temperature of the belt 310 in a mixed job, the temperature control unit 102 controls the temperature of the belt 310 so that the amount of temperature change during the job is reduced. This makes it possible to suppress interruptions in image formation due to temperature changes. As a result, it is possible to suppress the decrease in productivity caused by temperature changes in mixed jobs. [Explanation of Symbols]

[0081] 1. Image forming apparatus 101 Operation section 102 Temperature Control Unit 110 Acquisition Department 300 heating units 310 Fixing belt 320 pads 330 Pressure Roller 351 Heating roller 352 Thermistor 390 Halogen Heater F Fixing device

Claims

1. A heating rotor that applies heat to the recording material; A pressurizing rotor that pressurizes the heating rotor; The heating and pressure rotating members apply heat and pressure to the recording material, fixing the toner image onto the recording material; A temperature control unit that controls the temperature of the heating rotator; an acquisition unit for acquiring information regarding the basis weight of a recording material to be fixed; A job in which a plurality of recording materials are mixed, including a first recording material having a first basis weight and a second recording material having a second basis weight different from the first basis weight, is defined as a mixed job; In the mixed job, one mode can be executed from a plurality of modes including a first mode and a second mode, the first mode has a larger number of print sheets per unit time than the second mode, In the mixed job, when a plurality of recording materials are fixed, The temperature control unit is In the first mode, a first temperature determined based on the first basis weight and the second basis weight acquired by the acquisition unit is set as a target temperature for fixing the first sheet of recording material, and a second temperature determined based on the first basis weight and the second basis weight acquired by the acquisition unit is set as a target temperature for fixing the second sheet of recording material, in the second mode, a third temperature is set as a target temperature based on the first basis weight and not on the second basis weight for fixing the first sheet of recording material, and a fourth temperature is set as a target temperature based on the second basis weight and not on the first basis weight for fixing the second sheet of recording material; a difference between the first temperature and the second temperature being smaller than a difference between the third temperature and the fourth temperature.

2. the recording material of the first basis weight is a coated paper, and the recording material of the second basis weight is an uncoated paper, In the mixed job, when a plurality of recording materials are fixed, in the first mode, a fifth temperature is used for fixing the recording material of the first basis weight, and a second temperature is used for fixing the recording material of the second basis weight; in the second mode, a sixth temperature is used for fixing the recording material of the first basis weight, and a fourth temperature is used for fixing the recording material of the second basis weight, and a difference between the fifth temperature and the second temperature is smaller than a difference between the sixth temperature and the fourth temperature; a temperature control unit that sets the temperature based on the information acquired by the acquisition unit, the temperature being related to a basis weight of a predetermined number of sheets of recording material; and a fixing device that is characterized in that the acquisition unit acquires the information related to a basis weight of a predetermined number of sheets of recording material, the temperature being related to the information acquired by the acquisition unit.

3. The fixing device according to claim 1 or 2, characterized in that when fixing of recording material is performed in a job in which the number of sheets exceeds the information of the recording material that the acquisition unit can acquire, the acquisition unit acquires the information of the recording material excluding the recording material for which fixing has been completed, and the temperature is set based on the information acquired by the acquisition unit.

4. the first mode is capable of executing one of a plurality of modes including a third mode in the mixed job; In the mixed job, when a plurality of recording materials are fixed, in the third mode, a first temperature is used for fixing the recording material of the first basis weight, and a second temperature is used for fixing the recording material of the second basis weight; in the second mode, a third temperature is used for fixing the recording material of the first basis weight, and a fourth temperature is used for fixing the recording material of the second basis weight, such that a difference between the first temperature and the second temperature is smaller than a difference between the third temperature and the fourth temperature; The fixing device according to claim 1 , wherein the acquisition unit acquires the information regarding the basis weight of a predetermined number of sheets of recording material, and the temperature control unit sets the temperature based on the information acquired by the acquisition unit.

5. Furthermore, the first mode can execute one of a plurality of modes including a fourth mode and a fifth mode in the mixed job, The fixing device according to claim 4, characterized in that the fourth mode has a larger number of prints per unit time for a job that includes recording materials having a predetermined basis weight or more than the fifth mode, and the fifth mode has a larger number of prints per unit time for a job that includes recording materials having a predetermined basis weight or less than the fourth mode.

6. The fixing device according to claim 5 , wherein when the third mode is used for fixing, a mode to be used for fixing is selected from a plurality of modes included in the first mode based on the information acquired by the acquisition unit.

7. 7. The fixing device according to claim 6, wherein when the third mode is used for fixing, a mode to be used for fixing is selected from the plurality of modes included in the first mode so that the amount of change in the temperature is the smallest among the modes included in the first mode.

8. 8. The fixing device according to claim 5, wherein, when the first mode is used for fixing, the mode to be used for fixing can be selected from a plurality of modes included in the first mode.

9. 9. The fixing device according to claim 1, wherein the first temperature and the second temperature are the same.

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